Dye sensitized solar cells with a plastic counter electrode of poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate)

摘要

We report on dye sensitized solar cells with PEDOT-PSS coated directly on flexible polyester substrate as counter electrode. The behavior of such plastic counter electrode in the presence of I - /I3 redox electrolyte has been investigated with X-ray photoelectron spectroscopy. We have found that some of iodine species are "trapped" within the PEDOT-PSS layer. The presence of I3 - , I2 and PEDOT charge transfer complexes with iodine species may block the surface of the electrode. Furthermore, the PEDOT may be further oxidized (p-doped) during cell operation, which in turn may cause over oxidation and loss of conductivity in the PEDOT-PSS film. The interactions between PEDOT and iodine species may be enlarged because of the partial loss of PSS protective counter ion. The result is a decrease of PEDOT-PSS catalytic activity for reduction of I3 - to I - in the redox electrolyte and worse cell performance than in the case of DSSC with Pt counter electrode.